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Text File  |  2002-10-03  |  6.8 KB  |  154 lines
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  4. ffffggggllllOOOOrrrrtttthhhhoooo((((3333GGGG))))                   OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee                   ffffggggllllOOOOrrrrtttthhhhoooo((((3333GGGG))))
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  8. NNNNAAAAMMMMEEEE
  9.      ffffggggllllOOOOrrrrtttthhhhoooo - multiply the current matrix with an orthographic matrix
  10.  
  11.  
  12. FFFFOOOORRRRTTTTRRRRAAAANNNN SSSSPPPPEEEECCCCIIIIFFFFIIIICCCCAAAATTTTIIIIOOOONNNN
  13.      SUBROUTINE ffffggggllllOOOOrrrrtttthhhhoooo( REAL*4 _l_e_f_t,
  14.                           REAL*4 _r_i_g_h_t,
  15.                           REAL*4 _b_o_t_t_o_m,
  16.                           REAL*4 _t_o_p,
  17.                           REAL*4 _n_e_a_r,
  18.                           REAL*4 _f_a_r )
  19.  
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  21. PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRRSSSS
  22.      _l_e_f_t, _r_i_g_h_t Specify the coordinates for the left and right vertical
  23.                  clipping planes.
  24.  
  25.      _b_o_t_t_o_m, _t_o_p Specify the coordinates for the bottom and top horizontal
  26.                  clipping planes.
  27.  
  28.      _n_e_a_r, _f_a_r   Specify the distances to the nearer and farther depth
  29.                  clipping planes.  These values are negative if the plane is
  30.                  to be behind the viewer.
  31.  
  32. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  33.      ffffggggllllOOOOrrrrtttthhhhoooo describes a transformation that produces a parallel projection.
  34.      The current matrix (see ffffggggllllMMMMaaaattttrrrriiiixxxxMMMMooooddddeeee) is multiplied by this matrix and
  35.      the result replaces the current matrix, as if ffffggggllllMMMMuuuullllttttMMMMaaaattttrrrriiiixxxx were called
  36.      with the following matrix as its argument:
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  42.                       (                                      )
  43.                                  2__________
  44.                       |                       0           0        t  |
  45.                             right-left                         x
  46.                       |                                      |
  47.  
  48.                       |                       2__________               |
  49.                             0                           0        t
  50.                       |                  top-bottom             y |
  51.  
  52.                       |                                      |
  53.                                                        -2________
  54.                       |      0            0                  t  |
  55.                                                    far-near   z
  56.                       |                                      |
  57.  
  58.                       |     0           0          0      1  |
  59.  
  60.                       (                                     )
  61.  
  62.      where
  63.                                                   right + left____________
  64.                                 t  = -
  65.                                  x    right - left
  66.  
  67.                                                   top + bottom____________
  68.                                 t  = -
  69.                                  y    top - bottom
  70.  
  71.                                                  far + near__________
  72.                                  t  = -
  73.                                   z    far - near
  74.  
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  76.  
  77.      Typically, the matrix mode is GGGGLLLL____PPPPRRRROOOOJJJJEEEECCCCTTTTIIIIOOOONNNN, and (_l_e_f_t, _b_o_t_t_o_m,  -_n_e_a_r)
  78.      and (_r_i_g_h_t, _t_o_p,  -_n_e_a_r) specify the points on the near clipping plane
  79.      that are mapped to the lower left and upper right corners of the window,
  80.      respectively, assuming that the eye is located at (0, 0, 0).  -_f_a_r
  81.  
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  83.  
  84.                                                                         PPPPaaaaggggeeee 1111
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  91. ffffggggllllOOOOrrrrtttthhhhoooo((((3333GGGG))))                   OOOOppppeeeennnnGGGGLLLL RRRReeeeffffeeeerrrreeeennnncccceeee                   ffffggggllllOOOOrrrrtttthhhhoooo((((3333GGGG))))
  92.  
  93.  
  94.  
  95.      specifies the location of the far clipping plane.  Both _n_e_a_r and _f_a_r can
  96.      be either positive or negative.
  97.  
  98.      Use ffffggggllllPPPPuuuusssshhhhMMMMaaaattttrrrriiiixxxx and ffffggggllllPPPPooooppppMMMMaaaattttrrrriiiixxxx to save and restore the current matrix
  99.      stack.
  100.  
  101. EEEERRRRRRRROOOORRRRSSSS
  102.      GGGGLLLL____IIIINNNNVVVVAAAALLLLIIIIDDDD____OOOOPPPPEEEERRRRAAAATTTTIIIIOOOONNNN is generated if ffffggggllllOOOOrrrrtttthhhhoooo is executed between the
  103.      execution of ffffggggllllBBBBeeeeggggiiiinnnn and the corresponding execution of ffffggggllllEEEEnnnndddd.
  104.  
  105. AAAASSSSSSSSOOOOCCCCIIIIAAAATTTTEEEEDDDD GGGGEEEETTTTSSSS
  106.      ffffggggllllGGGGeeeetttt with argument GGGGLLLL____MMMMAAAATTTTRRRRIIIIXXXX____MMMMOOOODDDDEEEE
  107.      ffffggggllllGGGGeeeetttt with argument GGGGLLLL____CCCCOOOOLLLLOOOORRRR____MMMMAAAATTTTRRRRIIIIXXXX
  108.      ffffggggllllGGGGeeeetttt with argument GGGGLLLL____MMMMOOOODDDDEEEELLLLVVVVIIIIEEEEWWWW____MMMMAAAATTTTRRRRIIIIXXXX
  109.      ffffggggllllGGGGeeeetttt with argument GGGGLLLL____PPPPRRRROOOOJJJJEEEECCCCTTTTIIIIOOOONNNN____MMMMAAAATTTTRRRRIIIIXXXX
  110.      ffffggggllllGGGGeeeetttt with argument GGGGLLLL____TTTTEEEEXXXXTTTTUUUURRRREEEE____MMMMAAAATTTTRRRRIIIIXXXX
  111.  
  112.  
  113. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  114.      ffffggggllllFFFFrrrruuuussssttttuuuummmm, ffffggggllllMMMMaaaattttrrrriiiixxxxMMMMooooddddeeee, ffffggggllllMMMMuuuullllttttMMMMaaaattttrrrriiiixxxx, ffffggggllllPPPPuuuusssshhhhMMMMaaaattttrrrriiiixxxx, ffffggggllllVVVViiiieeeewwwwppppoooorrrrtttt
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  150.                                                                         PPPPaaaaggggeeee 2222
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